The immobilization of proteins on biodegradable polymer fibers via click chemistry

A facile and efficient method to immobilize bioactive proteins onto polymeric substrate was established. Testis-specific protease 50 (TSP50) was immobilized on ultrafine biodegradable polymer fibers, i.e., (1) to prepare a propargyl-containing polymer P(LA90-co-MPCIO) by introducing propargyl group into a cyclic carbonate monomer (5-methyl-5-propargyloxycarbonyl-1,3-dioxan2-one, MPC) and copolymerizing it with L-lactide; (2) to electrospin the functionalized polymer into ultrafine fibers; (3) to azidize the TSP50, and (4) to perform the click reaction between the propargyl groups on the fibers and the azido groups on the protein.

A new oxidation state of aniline pentamer observed in water-soluble electroactive oligoaniline-chitosan polymer

A novel water-soluble electroactive polymer, aniline pentamer crosslinked chitosan (Pentamer-c-Chi), was prepared by condensation polymerization of the terminal carboxyl groups in aniline pentamer with the amino side groups in chitosan in aqueous solution. The carboxyl groups were activated by N-hydroxysuccinimide (NHS) and N,N'-dicyclohexylcarbodiimide (I)CC). The electrochemical behavior of aniline pentamer in this kind of crosslinked polymer was studied in acidic aqueous solution by means of cyclic voltammetry (CV), UV-vis, and electron spin resonance (ESR) spectroscopy.

Effects of thermal annealing on polymer photovoltaic cells with buffer layers and in situ formation of interfacial layer for enhancing power conversion efficiency

We have investigated the effects of thermal annealing before and after cathode deposition on poly(3-hexylthiophene)(P3HT)/[6,6]-phenyl C61-butyric acid methyl ester (PCBM) blend photovoltaic cells with different cathode buffer layers. The introduction of cathode buffer layer such as lithium fluoride (LiF) and calcium oxide (CaO) in pre-annealing cells can increase the open-circuit voltage (V-oc) and the power conversion efficiency (PCE). Post thermal annealing after cathode deposition further enhanced the PCE of the cells with LiF/Al cathode.

Novel Sulfonated Polyimide Ionomers by Incorporating Pyridine Functional Group in the Polymer Backbone

A series of sulfonated polyimides (SPIs) containing pyridine ring in the polymer backbone were synthesized by the polycondensation of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTDA), 5-(2,6-bis(4-arninophenyl)pyridin-4-yl)-2-methoxy benzene sulfonic acid (SDAM), and 4,4'-diaminodiphenyl ether (ODA). Flexible, transparent, and tough membranes were obtained. Property study revealed that all the membranes displayed high thermal stability with the desulfonation and decomposition temperature higher than 290 and 540 degrees C, respectively, as well as good mechanical property with Young's modulus larger than 1.0 GPa, maximum strength (MS) on a scale of 60-80 MPa, and elongation at break (EB) ranged from 41.79 to 75.17%.

Application to polymer characterization by thermal analysis

The measured results of thermal analysis depend on experimental conditions. The international and national organizations have constituted a series of methods to characterize the physical and chemical properties for substances. The applications to physical transition, chemical reaction, and characteristic parameters of substances are given in the article as examples.

Effect of the work function of gate electrode on hysteresis characteristics of organic thin-film transistors with Ta2O5/polymer as gate insulator

Organic thin-film transistors (OTFTs) using high dielectric constant material tantalum pentoxide (Ta2O5) and benzocyclobutenone (BCBO) derivatives as double-layer insulator were fabricated. Three metals with different work function, including Al (4.3 eV), Cr (4.5 eV) and Au (5.1 eV), were employed as gate electrodes to study the correlation between work function of gate metals and hysteresis characteristics of OTFTs. The devices with low work function metal Al or Cr as gate electrode exhibited high hysteresis (about 2.5 V threshold voltage shift). However, low hysteresis (about 0.7 V threshold voltage shift) OTFTs were attained based on high work function metal Au as gate electrode.

Electrodeposition of platinum nanoclusters on type I collagen modified electrode and its electrocatalytic activity for methanol oxidation

We firstly reported a novel polymer matrix fabricated by type I collagen and polymers, and this matrix can be used as nanoreactors for electrodepositing platinum nanoclusters (PNCs). The type I collagen film has a significant effect on the growth of PNCs. The size of the platinum nanoparticles could be readily tuned by adjusting deposition time, potential and the concentration of electrolyte, which have been verified by field-emitted scanning electron microscopy (FE-SEM). Furthermore, cyclic voltammetry (CV) has demonstrated that the as-prepared PNCs can catalyze methanol directly with higher activity than that prepared on PSS/PDDA film, and with better tolerance to poisoning than the commercial E-TEK catalyst. The collagen-polymer matrix can be used as a general reactor to electrodeposit other metal nanostructures.

Novel NIR-absorbing conjugated polymers for efficient polymer solar cells: effect of alkyl chain length on device performance

Three low bandgap conjugated polymers, i.e., PDTPBT-C8, PDTPBT-C6 and PDTPBT-C5, which consist of alternating N-alkyl dithieno[3,2-b: 2',3'-d] pyrrole and 2,1,3-benzothiadiazole units and carry 1-octylnonyl, 1-hexylheptyl and 1-pentylhexyl as side chains, respectively, were synthesized. These polymers show strong absorption in the wavelength range of 600-900 nm with enhanced absorption coefficient as the length of alkyl chain decreases. The film morphology of the polymers and 1-(3-methoxycarbonyl) propyl-1-phenyl-[6,6]-C-61 (PCBM) blends is also dependent on the alkyl chain length. As the length decreases, the film becomes more uniform and the domian size decreases from 400-900 nm for PDTPBT-C8 to similar to 50 nm for PDTPBT-C5.

Solvent size effect on the static and dynamic properties of polymer chains in athermal solvents

The static and dynamic properties of polymer chains in athermal solvents with different sizes are studied by molecular dynamics method. With increasing solvent size, the radius of gyration and the diffusion coefficient of the polymer decay fast until a critical solvent size is reached. For the polymer diffusion coefficients, this decay only depends on the solvent size; while for the radius of gyration of polymers, this decay depends on both solvent size and the length of the polymers. The increase of solvent size also makes the polymer tend to be thicker ellipsoid until a critical solvent size is reached. The static scaling exponent of the polymer also shows the solvent size dependence. Moreover, four regions are identified where the polymers show different dynamic behaviors according to the dynamic structure factors of the polymer.

Composition effect on dewetting of ultrathin films of miscible polymer blend

Two kinds of dewetting and their transition induced by composition fluctuation due to different composition in blend [poly(methyl methacrylate) (PMMA) and poly(styrene-ran-acrylonitrile) (SAN)] films on SiOx substrate at 145 degrees C have been studied by in-situ atomic force microscopy (AFM). The results showed that morphology and pathway of dewetting depended crucially on the composition. Possible reason is the variation in intensity of composition fluctuation resulted from the change of components in polymer blend. Based on the discussion of this fluctuation due to the composition gradient, parameter of U-q0/E, which describes the initial amplitude of the surface undulation and original thickness of film respectively, has been employed to distinguish the morphologies of spontaneous dewetting including bicontinuous structures and holes.

Investigation of the dewetting inhibition mechanism of thin polymer films

The mechanism of inhibition of polymer film dewetting is investigated by adding a star comb-like polymer, four-arm P(S-ran-VB-g-PMMA), to PS film and PMMA film on different substrates. It is found that the mechanism of inhibition of polymer film dewetting is kinetic in nature, and is related to the miscibility between the additional compound and the polymer film. On addition to the miscible system [four-arm P(S-ran-VB-g-PMMA) and PMMA], the star comb-like polymers can increase the resistant force of dewetting with hole growth and inhibit the dewetting process of the thin polymer film by enrichment in the rim.

Microphase Separation of Mixed Polymer Brushes: Dependence of the Morphology on Grafting Density, Composition, Chain-Length Asymmetry, Solvent Quality, and Selectivity

Microphase separation of binary mixed A/B polymer brushes exposed to different solvents is studied using Single-Chain-in-Mean-Field simulations. Effects of solvent quality and selectivity, grafting density, composition, and chain-length asymmetry are systematically investigated, and diagrams of morphologies in various solvents are constructed as a function of grafting density and composition or chain-length asymmetry. The structure of the microphase segregated morphologies lacks long-range periodic order, and it is analyzed quantitatively Using Minkowski measures.

White Electroluminescence from a Phosphonate-Functionalized Single-Polymer System with Electron-Trapping Effect

A novel strategy for obtaining white electroluminescence (EL) is based on the mechanism of electron trapping on host. Phosphonate-functionalized polyfluorene is chosen as host owing to its strong electron affinity. Electrons are confined mostly by host pendants in the EL process, which suppresses charge transfer from host to dopant. White EL with CIE coordinates of (0.34,0.35) is achieved.

Sulphonated Tetramethyl Poly(ether ether ketone)/Epoxy/Sulphonated Phenol Novolac Semi-IPN Membranes for Direct Methanol Fuel Cells

The sulphonated phenol novolac (PNBS) which was used as a curing agent of epoxy was synthesised from phenol novolac (PN) and 1,4-butane sultone and confirmed by FTIR and H-1 NMR. The degree of sulphonation (DS) in PNBS was calculated by H-1 NMR. The semi-IPN membranes composed of sulphonated tetramethyl poly(ether ether ketone) (STMPEEK) (the value of ion exchange capacity is 2.01 meq g(-1)), epoxy (TMBP) and PNBS were successfully prepared. The semi-IPN membranes showed high thermal properties which were measured by differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) With the introduction of the corss-linked TMBP/PNBS, the mechanical properties, dimensional stability, methanol resistance and oxidative stability of the membranes were improve in comparison to the pristine STMPEEK membrane.

Novel sulfonated poly(arylene ether ketone) copolymers bearing carboxylic or benzimidazole pendant groups for proton exchange membranes

A novel strategy in which the benzimidazole group and sulfonic group are simultaneously attached to an aromatic polymer has been reported in this paper. For this purpose, sulfonated poly(arylene ether ketone) copolymers containing carboxylic acid groups (SPAEK-x-COOH, x refers to the molar percentage Of sulfonated repeating units) are prepared by the aromatic nucleophilic polycondensation of sodium 5,5'-carbonyl-bis(2-fluobenzene-sulfonate) (SDFBP), 4,4'-difluorobenzophenone (DFBP) and phenolphthalin (PPL). Then the carboxylic acid groups attached to the SPAEK-x-COOH are transformed to benzimidazole units through condensation reactions (referred to as SPAEK-x-BI). Fourier transform infrared spectroscopy and H-1 NMR measurements are used to characterize and confirm the structures of these copolymers.